This invention relates to a novel class of ortho or meta-alkoxycarbonylbenzyltrialkylphosphonium salts and to a method for regulating the natural growth or development of plants using said class of phosphonium compounds. The compounds of this invention are plant regulators which are defined by Congress in Public Law 92-516, the Federal Environmental Pesticide Control Act of 1972, section 2, subsection v, as any substance or mixture of substances intended through physiological action, for accelerating or retarding the rate of growth or rate of maturation, or for otherwise altering the behavior of plants or the produce thereof, but shall not include substances to the extent that they are intended as plant nutrients, trace elements, nutritional chemicals, plant inoculants, and soil amendments. In view of the ever increasing demand for plant products due to the rapid expansion of the world population, considerable research has been conducted to find chemical substances which can be beneficially utilized as plant regulators, such as, agents which retard vegetative growth or are useful for optimizing the yields of various crops.
Various phosphonium compounds are known. For example, U.S. Pat. No. 2,703,814 is directed to the preparation of phosphonium bromides and chlorides. U.S. Pat. No. 3,230,069 and U.S. Pat. No. 3,268,323 are directed to classes of phosphonium compounds useful for the regulation of plant growth. Another class of phosphonium compounds is described in U.S. Pat. No. 3,281,365, useful in antiseptic detergent compositions. A further class of phosphonium compounds useful for controlling nematodes is shown in U.S. Pat. No. 3,642,989.